Hi ya'll!

We just finished building a lot of 48-boards through SMT. Out of that 48
there was one board that we just discovered a big delamination blister on the
backside...it's about 1.5" wide and maybe 2.5 - 3" long. There was no rework
done on the board, and it was reflowed under the same profile in a
Conceptronic HVA-70 that the rest of them were...and they don't exhibit any
problems. There no sign of overheating at all around the blister, and the
silkscreen is nice and bright white...we just have this big blister. What
might cause that? The boards are polyimide. We didn't bake them, and they
were real fresh boards date code was 0300. Like I said, it was the only board
that had a problem...the rest are fine.

TIA

-Steve Gregory-

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